Motoyasu Kobayashi
Kogakuin University, Japan
Title: Interaction between polymer brushes bearing phophorylcholine and inverse: Phophorylcholine groups
Biography
Biography: Motoyasu Kobayashi
Abstract
Phosphocholine (PC) is a zwitterion group which can be found in phosphatidylcholine lipids of the cell membrane in nature. It is widely known that the polymer bearing PC group reveals excellent bio-compatibility and antifouling properties due to extremely weak interaction between PC and protein molecules. In this work, an adhesive interaction of polyzwitterion brushes containing sulfo- and phospho-betaine groups in water was estimated by force curve measurement using scanning probe microscopy. Polyzwitterion brushes with a 110 nm thick (dry state) on a silicon wafer were prepared by surface-initiated atom transfer radical polymerization of methacrylate monomers bearing sulfobetaine (SB), PC, and inverse-PC (iPC). Inverse PC is a zwitterionic group having inverted charge orientation of quaternary amine and phosphate in contrast to PC. Chemical structure of polymers with PC and iPC
Force curve measurement on (a) poly(MPC) brush and (b) poly(MiPC-iPr) brush surface in water by using PC or iPC functional groups-immobilized silica probe Force curve measurement were performed by atomic force microscopy using a handmade sphere probe. Silica particle (d = 20 μm) covered with SB, PC, and iPC functional groups was immobilized at the edge of a tipless cantilever with a small amount of epoxy resin. Adhesion force on the surface of SB and PC brushes were lower than 1 nN, whereas larger force than 20 nN was obtained between PC and iPC brush (Figure 2). A specific strong attractive interaction between PC and iPC were clearly observed. Poly(SB) brushes showed temperature dependency of adhesive interaction corresponding to the UCST behavior in water.